Chronic Pain: Hope Through Research

When you complain of headache or low back pain and the
doctor says take two aspirins every 4 hours and stay in bed, you
may think your pain is being dismissed lightly. Not at all.
Aspirin, one of the most universally used medications is an
excellent painkiller. Scientists still cannot explain all the
ways aspirin works, but they do know that it interferes with pain
signals where they usually originate, at the nociceptive nerve
endings outside the brain and spinal cord: peripheral nerves.
Aspirin also inhibits the production of chemicals manufactured in
the blood to promote blood clotting and wound healing:
Prostaglandins. Unfortunately, prostaglandins, released from
cells at the site of injury, are pain-causing substances. They
actually sensitize nerve endings, making them -- and you -- feel more
pain Along with increasing the blood supply to the area, the
chemicals contribute to inflammation -- the pain, heat, redness and
swelling of tissue damage.

Some investigators now think that the continued release of
pain-causing substances in chronic pain conditions may lead to
long-term nervous system changes in some patients that make them
hypersensitive to pain. People suffering such hyperalgesia can
cry out in pain at the gentlest touch, or even when a soft breeze
blows over the affected area. In addition to the prostaglandins,
blister fluid and certain insect and snake venoms also contain
pain-causing substances. Presumably these chemicals alert you to
the need for care-a fine reaction in an emergency, but not in
chronic pain.

There are several prescription drugs that usually can
provide stronger pain relief than aspirin. These include the
opiate-related compounds codeine, propoxyphene (Darvon®),
morphine, and meperidine (Demerol®). All these drugs have some
potential for abuse, and may have unpleasant and even harmful
side effects. In combination with other medications or alcohol,
some can be dangerous. Used wisely, however, they are important
recruits in the chemical fight against pain.

In the search for effective analgesics physicians have
discovered pain-relieving benefits from drugs not normally
prescribed for pain. Certain antidepressants as well as
antiepileptic drugs are used to treat several particularly severe
pain conditions, notably the pain of shingles and of facial
neuralgias like tic douloureux.

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Interestingly, pain patients who benefit from
anti-depressants report pain relief before any uplift in mood.
Pain specialists think that the antidepressant works because it
increases the supply of a naturally produced neurotransmitter,
serotonin. (Doctors have long associated decreased amounts of
serotonin with severe depression.) But now scientists have
evidence that cells using serotonin are also an integral part of
a pain-controlling pathway that starts with endorphin-rich nerve
cells high up in the brain and ends with inhibition of
pain-conducting nerve cells lower in the brain or spinal cord.
Antidepressant drugs have been used successfully in treating the
excruciating pain that can follow an attack of shingles.

Antiepileptic drugs have been used successfully in treating
tic douloureux, the riveting attacks of facial pain that affect
older adults. The rationale for the use of the antiepileptic
drugs (principally carbamazepine -- Tegretol®) does not involve the
endorphin system. It is based on the theory that a healthy
nervous system depends on a proper balance of incoming and
outgoing nerve signals. Tic and other facial pains or neuralgias
are thought to result from damage to facial nerves. That means
that the normal flow of messages to and from the brain is
disturbed. The nervous system may react by becoming
hypersensitive: It may create its own powerful discharge of nerve
signals, as though screaming to the outside world "Why aren't you
contacting me?" Antiepileptic drugs -- used to quiet the excessive
brain discharges associated with epileptic seizures -- quiet the
distress signals associated with tic and may relieve pain that
way.

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